纳氏试剂比色法测定水体中氨氮影响因素的探讨

对纳氏试剂比色法测定水中氨氮的条件进行了优化,根据实际分析工作中的经验,对实验中出现的常见问题和解决办法进行了总结.     

Ecological impacts of early 21st century agricultural change in Europe – A review

The impacts of agricultural land use are far-reaching and extend to areas outside production. This paper provides an overview of the ecological status of agricultural systems across the European Union in the light of recent policy changes. It builds on the previous review of 2001 devoted to the impacts of agricultural intensification in Western Europe. The focus countries are the UK, The Netherlands, Boreal and Baltic countries, Portugal, Hungary and Romania, representing a geographical spread across Europe, but additional reference is made to other countries. Despite many adjustments to agricultural policy, intensification of production in some regions and concurrent abandonment in others remain the major threat to the ecology of agro-ecosystems impairing the state of soil, water and air and reducing biological diversity in agricultural landscapes. The impacts also extend to surrounding terrestrial and aquatic systems through water and aerial contamination and development of agricultural infrastructures (e.g. dams and irrigation channels). Improvements are also documented regionally, such as successful support of farmland species, and improved condition of watercourses and landscapes. This was attributed to agricultural policy targeted at the environment, improved environmental legislation, and new market opportunities. Research into ecosystem services associated with agriculture may provide further pressure to develop policy that is targeted at their continuous provisioning, fostering motivation of land managers to continue to protect and enhance them.     

上海市固体废弃物的产生源现状分析

从排污行业、单位类别，经济类型和企业规模上对目前上海市危险废物、一般废物和其他废物的现状进行综述，并初步探讨了固体废弃物的资源潜力和管理技术。     

On the sustainability of common property resources

We provide a model where a common property resource is managed by two types of agents, cooperators and non-cooperators, who adjust their extraction strategies in response to persistent differential payoffs. In our model, the social approval of cooperators works as a reward mechanism which, as we show, favors both the pervasiveness of cooperative behavior and the sustainable management of natural resources. Specifically, we show that in the presence of such a reward mechanism a stable equilibrium can be reached with both strategies being practiced simultaneously and a decentralized and sustainable management of common property resources is possible.     

Provisioning rules and chick competition in asynchronously hatching common terns (Sterna hirundo)

Interactions between nestling birds and their parents are models for examining parent–offspring communication and sibling competition. Most studies have focused on species where young are restricted to a nest. However, offspring of many species are mobile and fed by parents for an extended period post-hatch. These chicks mobility may provide an opportunity to examine the role of signalling and physical competition on parental feeding decisions. We examined parental provisioning rules in relation to offspring behaviour and hatching order (i.e., competitive ability) in a species with mobile young, the common tern. We determined that about 95% of feedings were directed to the first chick to reach the parent when it landed with food. We developed a probabilistic model to predict the likelihood of a chick reaching the parent first, and thus receiving food. Our model showed that begging intensity, feeding history, and the interaction between begging intensity and relative proximity to the parent best predicted which chick would arrive first. Increased begging was associated with arriving first significantly more when a chick was relatively further from the parent than when it was closer than its siblings. Independently of these factors, larger, earlier-hatched chicks were more likely to be fed than smaller, later-hatched chicks. Additional analyses showed that parents landed closer to more intensively begging chicks, however, increased begging did not explain the advantage of earlier-hatched chicks because begging intensity did not vary with hatching order. Instead, earlier-hatched chicks were more likely to outrun later-hatched siblings and reach the parent first.     

The effect of diesel fuel on common vetch (Vicia sativa L.) plants

When petroleum hydrocarbons contaminate soil, the carbon:nitrogen (C:N) ratio of the soil is altered. The added carbon stimulates microbial numbers but causes an imbalance in the C:N ratio which may result in immobilization of soil nitrogen by the microbial biomass, leaving none available for plant growth. As members of Leguminosae fix atmospheric nitrogen to produce their own nitrogen for growth, they may prove more successful at growing on petroleum hydrocarbon contaminated sites. During a wider study on phytoremediation of diesel fuel contaminated soil, particular attention was given to the performance of legumes versus other plant species. During harvesting of pot experiments containing leguminous plants, a recurring difference in the number and formation of root nodules present on control and contaminated Common vetch (Vicia sativa L.) plants was observed. The total number of nodules per plant was significantly reduced in contaminated plants compared to control plants but nodules on contaminated plants were more developed than corresponding nodules on control plants. Plant performance of Common vetch and Westerwold's ryegrass (Lolium multiflorum L.) was compared to illustrate any difference between the ability of legumes and grasses to grow on diesel fuel contaminated soil. Common vetch was less affected by diesel fuel and performed better in low levels of diesel fuel contaminated soil than Westerwolds ryegrass. The total amount of diesel fuel remaining after 4 months in Common vetch planted soil was slightly less than in Westerwolds ryegrass planted soil.     

Positive framing does not solve the tragedy of the commons

We investigate whether positive framing increases cooperation in three social dilemmas with slightly different properties: a linear public goods (PG) game, a non-linear PG game, and a common pool resource (CPR) game. Results from our laboratory experiments show that contributions to a linear PG are higher if the externality is framed positively, rather than negatively, corroborating earlier findings by Andreoni (1995). By contrast, we find no such framing effects in the non-linear PG game or the CPR game. In these games, the best response in the material payoffs is to contribute less if others contribute more, counteracting effects of pro-social preferences. Positive framing therefore does not help to solve the tragedy of the commons.     

Agricultural landscapes as multi-scale public good and the role of the Common Agricultural Policy

During the last 50 years, the Common Agricultural Policy (CAP) has impacted the evolution of European agricultural landscapes by driving changes in land use and farming practices. We propose a typology characterising the scales relevant for agricultural landscapes management and argue that action is required on three scales: (1) a landscape oriented management at the farm level; (2) the coordination of land managers’ actions at the landscape level; and (3) the conservation of the diversity of agricultural landscapes in the EU. We provide evidence that until now the CAP has mainly focused on the first scale. We also illustrate how agricultural policy could encourage coordinated actions at the landscape- and EU-scales. In particular, we propose policy instruments to coordinate actions of individual land owners (e.g. collective bonus in agro-environmental contracts or support to environmental cooperatives (scale 2)). We also analyse how the recognition and transposition of the European Landscape Convention could promote trans-frontier landscape cooperation in order, not only to conserve high-quality rural landscapes, but also to ensure the conservation of the diversity of EU landscapes (scale 3). This paper provides a knowledge base to support an integrated CAP design in the direction of improved landscape management, as an important component of the EU project towards more sustainable agriculture.     

Implementing the Water Framework Directive: Contract Design and the Cost of Measures to Reduce Nitrogen Pollution from Agriculture

The performance of different policy design strategies is a key issue in evaluating programmes for water quality improvement under the Water Framework Directive (60/2000). This issue is emphasised by information asymmetries between regulator and agents. Using an economic model under asymmetric information, the aim of this paper is to compare the cost-effectiveness of selected methods of designing payments to farmers in order to reduce nitrogen pollution in agriculture. A principal-agent model is used, based on profit functions generated through farm-level linear programming. This allows a comparison of flat rate payments and a menu of contracts developed through mechanism design. The model is tested in an area of Emilia Romagna (Italy) in two policy contexts: Agenda 2000 and the 2003 Common Agricultural Policy (CAP) reform. The results show that different policy design options lead to differences in policy costs as great as 200–400%, with clear advantages for the menu of contracts. However, different policy scenarios may strongly affect such differences. Hence, the paper calls for greater attention to the interplay between CAP scenarios and water quality measures.     

Policy implementation of catchment-scale flood risk management: Learning from Scotland and England

Recent years have seen a gradual adoption of a “catchment-scale” approach to flood risk management into European policy-making which, amongst other objectives, promotes rural land use change to reduce flood risk. While some exploratory studies of land managers’ attitudes exist, research is lacking on how public policies can be mobilised locally to implement these ideas. Two local initiatives were analysed in the transboundary River Tweed basin in Scotland and England during which public authorities negotiated with land managers. A combination of documents (N = 21) and interviews (N = 63) forms the basis of the data analysed. The results showed that implementation is highly dependent on the local policy framework, the activities of implementers, and land managers’ responses to (combination of) policy instruments. Several factors were identified influencing implementation such as devolution arrangements (i.e. from national to regional/local), the level of local interest on flood risk, local attitudes to compromise and collaboration, available policy instruments, and the existence of participatory catchment organisations. With limited scope for stand-alone regulatory action or funding in the short term, synergies and measures promoting co-benefits in flood risk management should be further sought in the Water Framework Directive River Basin Management Plans, as well as in cross-compliance and the new agri-environment-climate strategies of the common agricultural policy.